Electronic thermometers such as a thermometer for measuring temperature of water or air and a clinical thermometer for measuring a body temperature by selecting an armpit, oral cavity, ear canal, and the like of a human body as a measurement site have heretofore been proposed. In the thermometer for measuring the water or air temperature, and the clinical thermometer for measuring the body temperature by the armpit or the oral cavity of the human body use temperature sensors such as a thermistor are used. Moreover, in the clinical thermometer which uses the ear canal as the measurement site, infrared sensors such as a thermopile are used as a sensor for detecting infrared radiation from the ear canal.
Generally, there is a dispersion in individual electric characteristics in the sensors such as the thermistor and thermopile used in the electronic thermometers, and therefore outputs of which individual sensors need to be adjusted in order to constitute a thermometer with a predetermined precision.
To solve the problem, the present applicant has proposed PCT/JP98/04260 in a clinical thermometer of emission type in which output of the thermistor or the infrared sensor is adjustable. In the emission type clinical thermometer infrared radiation from an object to be measured is guided by a light guide tube, the radiation in detected by infrared sensor (first infrared sensor), the temperature of the infrared sensor is measured with a temperature-sensitive sensor (first temperature-sensitive sensor), and by using a second infrared sensor and second and third temperature-sensitive an influence of a temperature difference between the light guide tube and the infrared sensor is compensated for by using a second infrared sensor and second and third temperature-sensitive sensors, so that the temperature of an object whose temperature is to be measured is obtained. There is provided adjustment means to adjust respective outputs of the first and the second infrared sensors and the first to the third temperature-sensitive sensors. A higher-precision emission type clinical thermometer is provided by adjusting the dispersion of the electric characteristics of each sensor with the adjustment means in a manufacturing process.
As described above, in recent years, such higher-precision clinical thermometers have been demanded. In order to provide the clinical thermometer with a higher precision, even a value of a digit lower in order than a digit number displayed as a body temperature to a user of the thermometer needs to be adjusted within a predetermined range. For example, in a clinical thermometer designed to display the body temperature to a 1/10 digit value, the digit value of 1/100 of the body temperature is adjusted within the predetermined range.
However, there are problems that, in order to confirm whether or not the value of the digit lower in order than the digit number displayed as the body temperature to the user of the thermometer is adjusted in the predetermined range a special display which is able to display even the value of the digit lower than that on the main body of the clinical thermometer is used in the manufacturing process, separately from a display on the main body of the clinical thermometer, and that the number of digits of the display on the main body of the clinical thermometer has to be increased to obtain the lower digit which is not usually displayed. There are necessary only for adjustment in the manufacturing process, and cause an increase in a product cost.
Moreover, in case where the number of digits necessary for display differs for usual use and special use and the number of display digits necessary for the usual use which is required more frequently is smaller than the number of display digits necessary for the special use which is required less frequently, a display section needs to be constituted and adapted for the larger number of digits notwithstanding the fact that the frequency of use is low.
For example, in the clinical thermometer, three-digit display such as 37.2° C. is sufficient in a general clinical thermometer. However, four-digit display such as 37.24° C. is required for a clinical thermometer for women' use to record a periodical subtle change of the body temperature. Therefore, if the same clinical thermometer is used both for the general clinical thermometer and the clinical thermometer for women's use a four-digit display section is necessary, although a three-digit display section is sufficient for the usual use. This causes an increase in cost. Therefore, a clinical thermometer which can display a four-digit temperature using the three-digit display section is demanded.
It is an object of the present invention to solve the aforementioned problem, and to provide an electronic thermometer which is able to display all information to be displayed using a display section having a digit number smaller than that of the all information to be displayed.